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What to Know Before Getting a CT Scan Kapi'olani's program is tailored just for kids Kevin Kon, M.D. News stories in the past year about the frequency of CT scans and associated radiation dose, as well as the ongoing nuclear emergency in Japan, have created a certain amount of anxiety about radiation exposure. All the more reason, then, for parents to inform themselves and allay any apprehension in the event their physician recommends a computed tomography, or CT, scan for their child. While the scan will produce more exposure to radiation than conventional X-rays, there are occasions when a CT scan is a preferable choice among diagnostic tests to identify and monitor conditions, says Kapi'olani pediatric radiologist Kevin Kon, M.D. CT Scans: A Clearer Look Regular X-rays produce a single one-dimensional image. A CT scan directs a beam of X-rays across a specific part of the body while the patient lies on a special table. A detector then collects the information and produces a crosssectional image that provides better and more precise images of bones, soft tissues, and internal organs — and often does so more quickly than some other diagnostic scanning options. These can then be reprocessed into multidimensional views providing even further insight into medical conditions and diseases such as internal injuries or bleeding, muscle and bone problems, and more. In the past, locating such conditions often required exploratory surgery. Weighing Risks and Benefits The underlying premise for radiation exposure is that its effects are cumulative, so there is concern that additional exposures from medical scans may increase the risk for cancer. It is known, for example, that 20 to 25 persons among any 100 people will incur some form of cancer in their lifetimes. It is theorized that one abdominal CT scan at an adult dose may increase this occurrence by a small fraction. The theoretical estimate is one-fifth of 1 percent. We must balance this radiation risk with the ability of CT scanning to detect conditions that at times pose a much greater threat to us and our children if left undetected and untreated, Dr. Kon points out. At Kapi'olani, we strive to do just this by scanning only when we feel it's absolutely medically necessary, and limiting scanning only to that part of the body potentially involved. We avoid scanning patients as screening exams for vague and nonspecific complaints just to ensure that nothing is wrong. When scanning for symptoms such as abdominal pain or conditions like appendicitis, scans are limited to the area of interest, thus decreasing patient X-ray exposure. Specialized Imaging Care for Kids The physicians at Kapi'olani are specially trained in pediatric radiology, using imaging techniques to diagnose illnesses, injuries, and diseases found in infants, children, and adolescents. In addition to completing medical school and five years of training in diagnostic radiology, these pediatric specialists complete another year of training specifically in Pediatric Radiology. At Kapi'olani, this is further supplemented with a Certificate of Added Qualification in Pediatric Radiology (CAQ). Their expertise not only includes making the correct diagnoses but also ensuring that the most appropriate imaging exam is performed. As Hawai'i's only children's hospital, Kapi'olani emphasizes the use of the best techniques, scanning as few times as possible with the lowest possible levels of radiation, says Dr. Kon. "The levels we use in our machines are actually below the dose recommended by the American College of Radiology (ACR) while still allowing excellent diagnostic examinations. Doses from machines can vary, so we have worked with the program in our scanner to decrease the dose based on patient age and body size. Our technologists have worked to further reduce dose to the lowest radiation levels of any CT scanner in Hawai'i. We capture good diagnostic images but with less radiation. We use kid-sized doses, aiming to achieve the absolute minimum exposure to get the image needed to make a diagnosis," he adds. To illustrate, Dr. Kon notes that the average background radiation from naturally occurring sources such as buildings, soil, food, and drink is expressed as a dose of three millisieverts per year, or about .01 millisieverts per day. For comparison, an adult chest X-ray is about 10 times more at 0.1 millisieverts or the equivalent of about 10 days of background radiation. For a CT scan of the head, the average quoted adult dose is usually two millisieverts, or about eight months of background radiation. For children at Kapi'olani, our dosages are below that level. Easing the Anxiety of a CT Scan Besides tailoring the techniques and doses of CT scans to the needs of kids, Kapi'olani recently decorated its CT scanning suite in an aquatic theme — fish on the wall and bubbles on the ceiling. "It's a happy, friendly, welcoming environment," says the pediatric radiologist. "Our goal is to make it a more pleasurable experience. We hope the new suite will decrease the need for sedation in our younger children, and put the older ones more at ease so they can cooperate better, minimizing motion and reducing the time for the procedure." Be an Informed Decision-Maker Dr. Kon encourages parents to speak with their physician before a CT scan and inquire what other options may be available. "We prefer to use ultrasound whenever possible before a CT scan," he says. "But ultrasound doesn't image well through air or bone, which can sometimes limit what we see. Another possibility is magnetic resonance imaging, or MRI. However, it takes longer than a CT scan, is very sensitive to motion and requires younger kids to be sedated. Sometimes, a CT scan will provide a diagnosis more quickly. Parents and pediatricians must discuss and weigh the risks versus benefits of CT scanning and proceed when believed to be medically necessary." Looking for a pediatrician? Visit www.kapiolani.org and select the link for Kapi'olani Medical Center for Women and Children. Then click on "Physician Directory" on the left to search for physicians by name, location, or specialty.